common/models/LoginForm.php

<?php
namespace common\models;
use Yii;
use yii\base\Model;
/**
 * LoginForm is the model behind the login form.
 */
class LoginForm extends Model
{
    public $username;
    public $password;
    public $rememberMe = true;
    
    private $_user = false;
    /**
     * @return array the validation rules.
     */
    public function rules()
    {
        return array(
            // username and password are both required
            array(array('username', 'password'), 'required'),
            // password is validated by validatePassword()
            array('password', 'validatePassword'),
            // rememberMe must be a boolean value
            array('rememberMe', 'boolean'),
        );
    }
    /**
     * Validates the password.
     * This method serves as the inline validation for password.
     */
    public function validatePassword()
    {
        $user = $this->getUser();
        if (!$user || !$user->validatePassword($this->password)) {
            $this->addError('password', 'Incorrect username or password.');
        }
    }
    /**
     * Logs in a user using the provided username and password.
     * @return boolean whether the user is logged in successfully
     */
    public function login()
    {
        if ($this->validate()) {
            return Yii::$app->user->login($this->getUser(), $this->rememberMe ? 3600*24*30 : 0);
        } else {
            return false;
        }
    }
    /**
     * Finds user by [[username]]
     *
     * @return User|null
     */
    private function getUser()
    {
        if ($this->_user === false) {
            $this->_user = User::findByUsername($this->username);
        }
        return $this->_user;
    }
}